Voiding Dysfunction

Question 1

CNS innervation of voiding

Answer 1

Voluntary control over micturition
Inhibition of reflex detrusor contraction

Question 2

Parasympathetic innervation of voiding

Answer 2

Facilitates macutrition

Direct motor activation of detrusor contraction
Indirect facilitation of detrusor contraction via stretch receptors

Question 3

Sympathetic innervation of voiding

Answer 3

Facilitates storage

Inhibition of detrusor via direct (beta-3-adrenergics) and indirect (blocking PSNS) routes
Contraction of “internal sphincter”/bladder neck

Question 4

What part of the urinary tract is under somatic control?

Answer 4

External sphincter

Question 5

Describe the micturition reflex

Answer 5

• Autonomic reflex between bladder and spinal cord promoting bladder emptying
• Urine causes stretching of bladder wall, promotes detrusor contraction
• Further activation of stretch receptor with further promotion of detrusor contraction

Question 6

CNS mediation of the micturition reflex

Answer 6

• Can inhibit it
• Decision to urinate is made, CNS removes the inhibitory signals and external sphincter relaxes to allow for micturition reflex to occur

Question 7

How does the pontine micturition center coordinate voiding?

Answer 7

Detrusor contraction – PNS
Internal sphincter relaxation – inhibition of SNS
External sphincter relaxation
Damage to brainstem/pons or spinal cord lesion below have potential to cause discoordination

Question 8

What is the micturition cycle?

Answer 8

Question 9

Overactive bladder
What is the fundamental pathoglogy?
What are the sx?

Answer 9

Hyperactive/irritable detrusor – “Bladder spasms”
Urinary urgency, frequency, nocturia, urge incontinence

Question 10

What are the causes of OAB?

Answer 10

• UTI
• Bladder irritants
• Neurologic conditions – Spinal cord injury, stroke, MS
• Metabolic conditions – Diabetes
• Urethral obstruction – Enlarged prostate, prior surgery for incontinence
• Other – Lack of estrogen, obesity, pelvic organ prolapse, pelvic floor dysfunction

Question 11

What is the epidemiology of OAB?

Answer 11

Common
Rises with age
<70 yo:F
>70 yo: M=F

Question 12

What is the tx for OAB?

Answer 12

Behavioral therapies – Fluid management, Kegel exercises
Medications – Anti-cholinergics (oxybutin, tolterodine), beta (III)-adrenergic agonist (myrbetriq)
Surgery

Question 13

What kind of pathology does an underactive detrustor cause?

Answer 13

Chronic retention/overflow incontinence

Question 14

What pathology voiding incontience is associated with the urethral sphincter?
What is the pathophysiology?

Answer 14

Stress incontinence

Incontinence with coughing sneezing, exercise, exertion
Due to weakness of urinary sphincter and support structures of urethra and bladder neck

Question 15

What are the causes of stress incontinence?

Answer 15

Vaginal/pelvic trauma

Multiple vaginal deliveries
Pelvic surgery
External trauma
Often associated with vaginal prolapse

Lack of estrogen (menopause)
Neurologic (spina bifida)
Radiation therapy: Scarring
Obesity

Question 16

What is the epidemiology of stress incontinence?
What risk factors are associated?

Answer 16

40% of healthy females aged 30-49 have experienced some degree of incontinence with exercise
Up to 25% of women may experience incontinence 3 months following their first vaginal delivery

Risk of incontinence increases with
Number of children (vaginally > C-section)
Age older than 45 years

Question 17

What is the tx for stress incontinence?

Answer 17

• Behavioral therapies: Kegels, weight loss
• Medication (technically no approved drug for SUI): Duloxetine (SNRI)
• Increase neural output from spinal cord to EUS leading to contraction
• Surgery

Question 18

What are the causes of urinary retention?

Answer 18

Bladder (detrusor): Weak/underactive/atonic/areflexic
Causes: Neurogenic, myogenic, psychogenic, medication (anti-ACh, α-adrenergics, narcotics)

Urethral obstruction
Anatomic: Prostatic enlargement, urethral stricture, prior incontinence surgery
Functional
Neurogenic – Detrusor-sphincter dyssynergia (uncoordination)
Non-neurogenic – Dysfunctional voiding

Temporary retention - Post-op
Anesthetics have anticholinergic activity
Increased sympathetic tone
More likely if patient has concomitant risk factors

Question 19

What are the sx of urinary retention?

Answer 19

• Voiding difficulty/inability to urinate: straining, hesitancy, intermittent stream, weak urinary stream
• Urinary frequency (from lack of bladder emptying)
• Lower abdominal/suprapubic pain (acute)
• “Overflow” urinary incontinence (chronic)
• Suprapubic fullness/mass (distended bladder)
• Hydronephrosis/renal failure

Question 20

What is the tx for urinary retention?

Answer 20

• Catheter drainage of bladder: Indwelling, intermittent (ideal)
• Treat UTI
• Stop aggravating meds (anti-ACh)
• Relieve any obstruction(α-blocker medications, Surgery on prostate)
• Neuromodulation – Non-obstructive retention